Lactic Acid is often described as the intense burning or fatigue in the muscle during or post exercise. This is true, that is lactic acid. But scientifically, lactic acid is a three carbon, organic acid thats produced by anaerobic (without oxygen) respiration. Two types of lactic acid exists. D-lactic acid is a result of fermentation of dextrose. L-lactic acid is a product of glucose and glycogen and its metabolism. This is mostly involved in muscular contraction. L-lactic acid is also a racemic mixture that can be found in sour milk and in the stomach. Small amounts of L-lactic acid can also be found in small amounts in other foods. When oxygen becomes avaliable, lactic acid will be completely broken down to carbon dioxide and water.
If your lactate threshold has been "ran up" at a low level of exercise intensity, it pretty much means that the "oxidative energy systems" in your muscles are not working at their peak ability. If performing at a high level, they would use oxygen to break lactate down to carbon dioxide and water, stopping the flood of lactate from pouring into the blood. One can tell if his lactic acid threshold is low. Some signs your's might be low include:
-you are not getting enough oxygen inside your muscle cells
-you do not have proper amount, or the right combination of the enzymes necessary to oxidize pyruvate at high rates
-you do not have enough mitochondria in your muscle cells.
* Sodium bicarbonate (baking soda) is acutally banned by the Olympics and many other national organiations for its buffering effect on lacti acid, thus putting an athlete that uses it at an "unfair" advantage becuase of the training you can do without having to stop from the pain of lactic acid. Things like creatine also help your threshold of lactic acid, yet another advantage of creatine phosphate.
There are various supplements out there these days that prevent lactic acid but most of piss in the wind supplements and arent proven for fitness application. Thanks for your reading, YJ